Energy conservation has caused people to rely more on bicycles than on fuel burning vehicles, such as motorcycles. However, for a substantial number of people, especially people of middle age or older, the bicycle is difficult to operate as well as being a slow mode of transportation.
In order to overcome the above difficulties, it has been common to construct a light weight motorcycle which includes a small power assisting motor. These types of light weight motorcycles are generally referred to as "mopeds." The vehicle is manually operated through a series of pedals, similar to a bicycle, with the motor for the purpose of adding additional power. A "moped's" speed is usually limited to less than thirty miles per hour, which is usually adequate speed for short distance traveling.
At the present time, for one that has a bicycle and that individual wishes to acquire a "moped," that individual must buy another separate vehicle. It would be most desirable to provide, at a substantially lower cost, a power assisting device which would accomplish the objectives of the "moped," which would be mounted in conjunction with the bicycle thereby eliminating the need for the purchase of a completely separate vehicle.
Previously, such designs for power assisting devices for a bicycle have encountered certain undesirable effects. The device must be able to quickly compensate for bounce since the roadway that the vehicle will be traveling on will not be perfectly smooth. Additionally, the previous types of devices have been rather noisy. The previous devices have employed the use of a chain drive mechanism. A belt type of drive would be far more quiet in operation. However, belt types of drives have certain inherent disadvantages, such as the belts stretching which requires periodic tightening of the belt or replacement. In order to obtain the advantage of the quieter operated belt assembly, there is a need for a device which will compensate for wear and stretch and keep the belt assembly taut at all times. Also, such a device could function to keep the belt assembly taut during the time that the driving wheel is bouncing.